Telephone-exchange system



Dec." 29 1925.

' W. H. MATTHIES TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 6 Sheets-Sheet 1 Dec. 29 1925 w. H. MATTHIEIS v TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 6 Sheets-Sheet 2 Mum/0r [MW/am fi. Waxy/W5.

Dec. 29 1925- W. H. MATTHIES TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 6 Sheets-Sheet 5 Dec; 29 1925- w. H.-MATTHIES TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 6 Sheets-Sheet 5 bwb ' Dec. 29 1925- w. H. MATTHIES TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 6 Sheets-Sheet 6 Patented Dec. 29, 1925.

UNETEQ STATES PATENT QFFEQE.

WILLIAM H. MATTI-IIES, OF HACKEITSACK, IIEXV JERSEY, ASSIGNOR T WESTERN ELECTRIC COMPANY, INGORPGRATED, 0 NEW" YORK, 1 Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed ficcober 16., 1924. Serial No. 743,884.

To all tom it may concern.

Be it known that I, VVILLIAM H. Mrvrrrincs, a citizen of the United States of America, residing at Hackensack, in the county of Bergen and State of New Jersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone sys tems and more particularly to systems employing automatic switches for extending connections.

This invention is particularly applicable to telephone systems in which connections are established under the control of register senders.

It is an object of the present invention to provide improved means for associating a subscribers line with the selector switches for extending said line, and with the register sender for controlling said switches in their selective action.

A feature of the invention lies in the provision of a plurality of link circuits, one of which is always in readiness for use, and which are provided with means for connecting with a line finder and a register sender.

This and other features of the invention will be apparent from a consideration of the following description in connection with the drawings and appended claims.

Referring to the drawings, Fig. 1 shows one of a group of subscribers lines together with a trip circuit common to the group of lines.

Fig. 2 shows a start circuit serving a plurality of trip circuits.

Fig. 3 shows a line finder-district selector circuit for extending the line of Fig. 1 to subsequent selectors.

Fig. 4 shows one of a plurality of link circuits serving the start circuit of Fig. 2 and having access to the line finder-district selector circuit of Fig. 3. A portion of two other link circuits is also shown.

Fig. 5 shows a portion of a sender circuit adapted to be selected by the link circuit of Fig. 4:.

Fig. 6 shows in diagrammatic manner the switches and apparatus necessary to extend a call to subscriber in a mechanical oiiice.

Fig. 7 shows the manner in which the several figures of the drawing should be arranged to disclose the invention completely.

It is to be noted that Fig. 5 is a skeletonization of the sender of the copending application of O. H. Kopp, Serial No. 745,919, filed Oct. 16, 1924, and the same reference numerals are applied to corresponding portions of the two drawings.

Subscribers lines such as line 100 are connected to multiple terminals appearing before a plurality of line finders. These multiple terminals are arranged in a plurality of groups each group being served by a separate brush set on each finder and each group being divided into two subgroups. A trip circuit is provided indivdual to each group; a start circuit is provided for all the groups of lines served by the group of line finders; and a plurality of link circuits are provided for each group of lines and line finders. The line finders and link circuits are divided into two subgroups and each such subgroup normally serves calls in the corresponding subgroups of lines. The arrangement is such that, except when all link circuits are busy, a link circuit will be in readiness to serve a call and will be connected by its district finder to an idle line finder.

hen a call is initiated by a subscriber in a particular group, the trip circuit individual to the group, and the start circuit are taken for use by that line and means are provided for preventing the extension of a call in the other subgroup of the group or in any other group until a line finder has been started in search of this calling line. Means are also provided for preventing the extension of a second call in this group, until after simultaneous calls in other groups have been taken care of. The operation of the start circuit causes the line finder associated with the link circuit allotted for use to hunt for the calling line and also causes the link circuit to hunt for an idle sender. As soon as a particular link is taken for use with a call the next link is allotted to serve the next incoming call in the particular subgroups which they serve. As soon as a brush set on the line finder has been tripped the start circuit will be freed to permit the extension of calls in other groups. As soon as the line has been found the trip circuit of the group is freed by the line finder to extend another call in the same group provided no call is awaiting extension in another group. As soon as selections are completed the sender and link circuit are released by the district selector circuit and the link circuit immediately hunts for another idle district.

When the subscriber at substation 100 removes his receiver from the switchhook a circuit is closed for line relay 101 extending from battery through that relay, inner contact of relay 102 over the subscribefls loop to ground at theouter contact of relay 102. Relay 101operates and closes a circuit from battery, resistance 10%, through the winding of relay 103 to ground at the outer contact of relay 101.

The operation of relay 103 closes a circuit from battery, resistance 105 to ground at the outer right contact of relay 106. This circuit is in shunt of the winding of relay 103, which relay serves the second subgroup of the group to which line 100 belongs, thus preventing the extension of a call from that subgroup, while the trip circuit is in use with line 100. also closes a circuit from battery, through the winding of relay 200, conductor 133, outer left contact of relay 107, outermost left contact of relay 103 to ground.

Relay 200 operates and connects ground over its contact to the inner right armature of relay 107. lVhen relay 107 operates, as subsequently 7 described, it looks to this ground through its right winding and remains looked as long as relay 200 remains operated. With relay 107 operatechthe' operating circuit of relay 108remains open and hence any other incoming calls in this group must await the release of relay 107 before they can be extended. Since relay 200 operates as soon as relay 103 or relay 106 operates, it will remain operated as long as a call awaits attention in any subgroup served by the start circuit of Fig. 2. The relay of each trip circuit corresponding to relay 107 operates as each call is served and locks to the contact of relay 200-. W hen all waiting calls have been served thecircuit of relay 200 is opened and that relay releases, releasing the relay 107 to permit the extension of other calls. of relay 200 extends over the bacl: contact of relay 107, should simultaneous calls exist in all the groups served by the star circuit of Fig. 2, when one call has been served in each group and relay 107 of the last trip circuit has been operated, no circuit would exist for holding relay 2'00 operatedand that relay would release pe nittiug the relays 10? to release and close over their back contacts, circuits for again operating relay 200 should additional calls await atte ti.

In addition relay The operation'of relay 103- Since the circuit.

battery, over the back contact of relay 201, right winding of trip relay 108, inner left contact of relay 107, innermost left contact of relay 103, left contact of relay 109 to ground. Relay 108 operates in this circuit and closes a locking circuit for itself from ground, right contact of relay 109, left winding and inner left contact of relay 108, over the inner left back contact of the trip relays of the other groups of lines, conductor 129, right winding of start relay 201 to battery.

Relay 201 operates in this circuit. A circuit is now closed for relay 110 extending from battery through the winding of relay 110, right contact of relay 108, conductor 128, to ground at the outer right contact of relay 201. Relay 110. locks in an obvious circuit to ground at the left bacl; contact of relay 109. Relay 108, together with relay 103 prepares a circuit from the outer contact.

of relay 110, outer left front contact of relay 108, inner right contact of relay 103, conductor 131, left back contact of relay 202, outer left back contact of relay 203, conductor 206, upper contact of cam 101,upper contact of cam 402, brush 4:61 and its associated terminal, conductor 3'78, upper contacts of cam 301, winding of relay '302, to

battery, the line finder of Fig. 3 having been assumed to have been allotted for use by the switch 460 and the sequence switch 300 there fore standing in position 2.

The operation of relay 108 also closes a circuitfrom ground over its outer right contact, through the winding of the trip magnet 303, serving the group in which line 100 appears on the line finder frame, to battery. Relay 110 upon energizing closes a circuit from battery, throughthe left winding of relay 109, left Winding of.

relay 107, outer contact ofrelay 110 to ground. Relay 107 operates and looks through its right winding and inner right contact to the contact of relay 200. V

The operation of relay e02 closes a circuit from battery, through the winding of updrive magnet 301, middle left contact of relay 302, upper contact of cam 364-, left.

front contact of relay 302 to ground.

Under the control of the updrive magnet 30% the line finder shaft is moved upwards. Due to the operation of the trip magnet 303 the set of brushes serving the group of lines to which line 100 belongs is tripped. Then the magnet leaves the tripping Zone a circuit is closed from ground over brush 307, through commutator segment 305, up; per contacts of canr306, outer left normal contact of key 20 1, inner right contact and right winding of relay 201 to battery. Relay 201 is held operated in this circuit but the circuit through the locking winding of relay 108 is shunted and that relay releases, in turnreleasing the trip magnet 303. As soon as brush 307 leaves segment 305 the circuit of relay 201 is opened and that re lay releases again connecting battery to the operating windings of relay 108 and the corresponding relays in other trip circuits, so that subsequent calls may be served.

Relay 302 closes a locking circuit for itself over its inner left contact, right contact of cam 308, back contact of relay 320, commutator segment 321, brush 322, to ground, which is closed as soon as the line finder moves upward. Relay 302 also closes a circuit from battery, over the inner left contact of relay 205, right winding of rclay 203, conductor 207, left contacts of cam 403, brush 462, and its associated terminal, conductor 370, upper left contact of cam 311, right front contact of relay 302 to ground. The operation of relay 203 rcinoves ground from conductor 206 thus preventing the start of another line finder until the brushes are tripped. Relay.203 locks in a circuit from battery, over the outer left contact of relay 205, left winding and outer left front contact of relay 203, left back contact of relay 202, conductor 131, inner right contact of relay 103, outer left contact of relay 108, outer contact of relay 110 to ground. The operation of relay 203 also closes a locking circuit for relay 201 from battery, left contact and left Winding of relay 201, inner right contact of relay 203 to ground. The circuits just traced are established before relay 108 is released by the shunting action of commutator segment 305. As soon, however, as relay 108 deenergizes it opens the locking circuit of relay 203, restoring the start circuit to condition to serve subsequent calls.

When relay 302 operates it also closes a circuit from ground through its right front contact, upper left contact of cam 311, conductor 379, brush 462, and its associated contact, right contact of cam 404, upper left contact of cam 405, right winding of relay 406, winding of relay 407, upper left contact of cam 408, upper right contact of earn 409, resistance 410 to battery. Relays 406 and 407 operate, relay 406 closing a locking circuit for itself and relay 407 from battery, through resistance 410, upper right contact of earn 409, upper left contact of cam 408, Winding of relay 407, right winding of relay 406, contact of cam 411, contact of relay 406 to ground. Relay 407 closes a circuit from battery, through the winding of sequence switch magnet 400, upper contact of cam 412, contact of relay 407 to ground. Magnet 400 operates advancing the link circuit sequence switch to position 2.

In position 2 ground is connected from the right contact of cam 415 to brush 466 and its associated contact, conductor 375, lower right contact of cam 312, lower right contact of cam 313, left winding of relay 314 to battery. Relay 314 operates, but performs no function until the calling line has been found. Ground from the front contact of relay 406 is also extended over the contact of cam 411, upper left contact ol? cam 405, upper right contact of cam 404, left contacts of cam 403, conductor 207, right winding of relay 203, inner left contact of relay 205 to battery, holding relay 203 operated until the link circuit sequence switch is moved out of position 1. lVhen the lint: circuit sequence switch arrives in position 2 relays 406 and 407 release. The release of relay 407 completes a circuit from ground at the back contact of relay 407, upper right and lower left contact of cam 105, winding of magnet 437 to battery. lrlagnet 487 operates and closes an obvious circuit for magnet 488. Magnet 488 is the rotary magnet for sender selector switch 480 and causes the switch to rotate in. search of an idle sender.

An idle sender is characterized by the connection of battery, through a 150 ohm rcsistance, such as resistance 501, to conductor 502 and its corresponding terminal in the set engaged by brush fit-h the lint: circuit sequence switch in position 2 ground is connected over the upper right contact of cam 421, through the left winding of relay 406, lower contact of cam 413, right windin of relay 406, winding of relay 407, lower contact of cam 401, lower right contact of cam 402 to brush 483.

lVhen brush 483 encounters a terminal corresponding to an idle sender, to which battery is connected, relay 406 operates. short circuiting its left hand winding over its contact and the contact of cam 411, permltting relay 407 to operate in series with the right hand winding of relay 406. The operation of relay 407 opens the circuit cl magnet 487 and closes a circuit from battery through the winding of sequence switch magnet 400, upper contact of cam 412, front. contact of relay 407 to ground advancing the link sequence switch to position 3.

In position 3 a circuit is prepared exteuit ing from ground through the right and middle windings of relay 503, outer right back contact of relay 504, right back contact of relay 505, conductor 506, brush 484 of sender selector 480, lower left and upper right contacts of cam 408, brush 464 of district linder 460 to conductor 315, left contact of cam 316, left winding of relay 317 to battery, which circuit is not completed until the district circuit reaches position 3.

In the meantime the line finder shaft continues to move upwards until it reaches the terminal corresponding to the calling subscribers line. lVhen these terminals are encountered a circuit is completed from battery, through the right winding of relay 100 and resistance 111, inner front contact of through its left hand winding, left winding of relay 107, outer left contact of relay 110 to ground. The operation of relay 109 opens the locking circuit of relay 110 and relay 110 releases after an interval due to the fact that relay 110 is slow to release. Relay 320 opens the locking circuit of relay 302 and that relay releases as soon as brush 310 encounters an insulating segment of centering cam 309.

The release of relay 302 opens the circuit of updrive magnet 304 and stops the line.

finder on the calling subscribers line. It also connects battery through resistance 323 and its left back contact, lower right and upper left contacts of cam 324, inner back con tact of relay 317 resistance 325, brush 326, and terminal 327, over conductor 112, winding of cut-off relay 102 to ground. Relay 102 operates and releases line relay 101 removing the calling condition from terminal 380. The operation of relay 102 also opens the circuit ofrelay 110 permitting its re lease.

The release of relay 101 permits relay 103 to release and also opens the circuit of relay 320. The connection of battery with terminal 327 marks terminal 113 and the other multiple terminals of calling line 100 in the terminal banks of final selectors with reduced battery potential to render the line busy as such final selectors. The release of relay 302 also closes a circuit from battery through the winding of sequence switch n'iagnet 300, lower left contact of cam 323, outer right frontcontact of relay 314, right back contact of relay 302 to ground. Sequence switch 300 is advanced in this circuit. to position 3. I

lVhen sequence switch 300 leaves position 2 the circuit of relay 314 is opened and that relay releases. When the sequence switch 300 reaches position 3, the previously traced circuit for relays 503 and 317 is completed. Relay 317, being marginal, does not operate at this time. Relay 503 operates and closes anobvious circuit for relay 507 which in. turn closes a circuit from battery, through resistance 508, winding of relay 509, left front contact of relay 507 to ground. Relay 509 operates and looks over its outer left front contact. Relay 509 closes a circuit for relay 510 from battery, winding of relay 510,

to ground at the right front contact of relay 509 which circuit is also closed at the outer left front contact of relay 507. It also starts the timing switch, of which brush 602 forms a part, in the manner disclosed in the above identified application of O. H. Kopp. The operation of relay 510 closes an obvious circuit for relay 511 which in turn closes a circuit through the left winding of relay 512.

The operation of relay 512 opens the circuit previously traced from battery, through resistance 501, to relays 406 and 407 and these relays rel-case. The release of relay 407 closes a circuit from battery, through the winding of sequence switch magnet 400, lower right contact of cum 412, back contact of relay 407 to ground. Sequence switch 400 is advanced to position 4 from which position it is moved to position 5 by means of ground over the lower left contact of cam 4-12.

In position 5 of the link sequence switch I the dialing leads and the fundamental circuit leads are cut through directly from the district circuit to the sender circuit. The dialing circuit may be traced from battery, through the left winding of relay 606, conductor 637, sender selector brush 485, and its corresponding terminal, lower contacts of cam 414, district finder brush 465 and its corresponding terminal, conductor 382, lower contact of cam 329, winding of relay 330, right back contact of relay 317, line finder brush 331, terminal 332, conductor 116 through the subscribers substation, conductor 117, terminal 333, brush 334, middle left back contact of relay 317, left contact of cam 335, conductor 375, brush 466, and its associated terminal, lower left contact of cam 415, brush 486, and its associated terminal, left back contact of relay 513 to ground.

In position 5 of the link circuit sequence switch 400, relays 406 and 407 are connected in a circuit extending from brush 484, left contacts of cam 403, winding of relay 407, right winding of relay 406, upper contact of cam 4-13, tobrusli 464. The circuit of these relays is extended from these brushes as will be later described. When the dialing circuit above traced is completed, relay 606 operates and closes a circuit from battery, through the winding of relay 610, front con tact of relay 006, conductor 639, left back contact of relay 515 to ground. Relay 610 operates and closes a circuit from battery, through the winding of relay 609, right front contact ofrelay 010, and thence to ground. As soon as relay 609 operates the dialing tone circuit is completed as follows: from source of tone 607, right winding of relay 606, normal. terminal and brush 804 of register switch 800, contact of relay 609, and thence to ground.

relay Due to the closure ot this circuit a tone is induced in the left winding ot relay 605 and over the dialing circuit to the receiver of the SUlQSClllJQl'lS telephone to indicate that dialing may be, started. The subscriber now dials the number or" the wanted subscriber.

The registers of the sender are positioned, the translator 830 operated and selections made under the control of the sender as described in the copending application of O. H. Kopo, Serial No. 74 5310, liled Oct. 16, 1024. After the completion of final units selection with the district selector sequence switch 300 in position 10, sender control sequence switch, cams of which are disclosed the left of the vertical brokenline and above the horizontal broken line of Fig. 5, in position 7, andsender sequence switch 700 in position 15, a fundamental circuit is completed from battery at the incoming selector 300 through the otlico selector 901, terminal 386, brush 357, upper contact of: cam 358, mner left back contact 01"- re ay 359, conductor 37 8, brush 461 and its corresponding contact, upper right and lower left contacts of earn 402, brush 481 and its corresponding contact, inner right back contact of relay 504, upper left contact of earn 523, contact of earn 954, of the class sequence switch, winding of relay 7 02, back contact of relay 703, left winding of relay 704-, lower contact of earn 525, translator brush 832, compensating resistance 859, outer right back con tact oil relay 524, inner right contact of relay 507', brush 482 and its corresponding contact, lower left and upper right contacts of cam 404, brush 462 and its corresponding contact, conductor 379, lower ri 'ht and upper left contacts of earn 329, brush 355, terminal 385, through ofiice selector 901 to ground (not shown) at the incoming selector 900. Relays 702 and 704 operate and 704 looks throughits right winding, outer right contact of cam 731 to ground on the contact of relay 714. Relay 704 also closes a circuit from battery through the winding of relay 708, lower left contact of cum 731, to ground at the contact of relay 704. The operation of relay 708 closes a circuit from battery, upper contact of earn 519, windiru of the No. 0 counting relay, conductor 7 outer right front contact of relay 708, contact of cum 523, contact of stepping relay 702, contact of 0am 518 to ground. The No. 0 OUUIllllHlI relay operates in time circuit and closes the usual locking circuit ti l for itself through the *inding of the No. 0 counting relay and relay 703. ing selector then opens the fundamental circuit, permitting the operation of the No. 0

counting relay and relay 703. The opera-.

tion of the No. 0 counting relay closes a circuit from battery, winding of relay 524, inner left front contact of relay 708, front cont-act of the No. 0 counting re ay t 'vanced to position 12 in this circuit.

The incomground at the contact of relay 71L Relay operates and locks over its inner right contact to ground over the contact of cam Kelly 524 in operating closes a circuit through the winding of relay 504, inne: left cont: ct of relay No. 13 to 21 terminals and brush 602 ol time measure switch 000 to ground. Relay 524 opens the fundamental circuit and advances sequence switch 700 to position 17. lVhen sequence switch 700 leaves position 16, the circuit of relays 704 and 708 is opened and these relays releasc. clay 708 in releasing advances sequence switch 700 to position 13 in which position talking selection it: made.

W'hcn. relay 504 operated it opened the shunt around the right winding of relay 50-; and the high resistance right winding cluded in the circuit of relay 503, which circuit it will be remembered, includes the winding of relay 351, and the left winding of relay 317 in parallel. This increase in resistance decreases the current througl'i relay 351 to such an extent that it deenergizes. The release of relay 351 in turn releases relay 314 which closes a circuit from battery through the winding of sequence switch magnet 300, lower right and upper left contacts of earn 342, outer right back contact of relay 314, back contact of relay 312 to ground. Sequence switch 300 is ad- As soon as sequence switch 300 reaches position 11 ground is connected over the upper contact of earn 316, conductor 315, brush 464 and its corresponding terminal, upper contact of cam 413, right winding of relay 400, winding of relay 407, left contacts of cum 408, brush 484 and its corresponding terminal, right back contact of relay 505 to the right winding of relay 503. Since both sides of this relay are now connected to ground relay 503 releases. The release of relay 503 in turn releases relay 507 causing the operation of relay 505 and the release of relay 509 in turn. Talking selection now takes place as described in the application of O. H. Kopp, supra.

At the completion of talking selection the No. 0 counting relay is operated closing a circuit from ground at the contact of relay 711, front contact of the No. 0 counting relay, inner left back contact of relay 705. lower contact of cam 710, winding oi relay 515 to battery.

The operation of relay 5'15, connects battery, through resistance 501, and the right contact of relay 515, over the inner from contact of relay 505 in parallel with battery through the winding of relay 505 to corn ductor 506, and thence over the brush 431- and its corresponding terminal leit contacts of earn 408, winding of relay 407, right winding of relay 406, upper contact of cazn 413, brush 464 and its corresponding terminal, upper left contact of cam 316 to ground. Relays 406 and 407 operate in this circuit. The operation of relay 407 closes a circuit from battery through the winding of sequence switch magnet 400, upper right contact of cam 412, front contact of relay at cam 408 and that relay releases.

407 to ground. Sequence switch 400 advances in this circuit to position 6. The operation of relay 406 connects ground through its contact and the right contacts of cam 403, resistance 416, brush 463 and its corresponding terminal to conductor 366 to mark the district selector busy to other link circuits until ground is placed on conductor 366 over the upper left contact of cam 417, contact 418 of make busy jack 419, through resistance 416 and brush 463 in positions 5% to 6 of sequence switch 400 which keeps the district busy until the link circuit is disconnected. \Vhen switch 400 leaves position 5 the circuit of relays 406 and 407 is opened and these. relays release. Atthe same time the circuit of relay 505 is opened Switch 400 is moved to position 7 in a circuit from battery through the winding of sequence switch magnet 400, contact 420 of make busy jack 419, lower left contact of cam 417 to ground. When switch 400 arrives in position 7 ground is connected over the upper right contact of cam 421, left winding of relay 406, lower contact of cam 41.3, right winding of relay 406, winding of relay 407, upper left contact of cam 408, lower right contact of cam 409 to brush 463.

At the same time a circuit is completed from battery, through the winding of magnet'467, upper left contact of cam 404, upper right contact of earn 405, back contact of relay 407 to ground' lhlagnet467 operates and closes an obvious circuit for magnet 468. The energization of magnet 4681ctates the district finder switch 460 in search of an idle districtselector. An idle district selector is characterized by battery through 150 ohm resistance connected to a terminal of the are served by brush 463. As soon as brush 463 encounters a terminal to which battery is connected through 150 ohms, relay 406 is operated connecting ground through its contact and the upper contact of cam 411 to its right winding and the winding of. relay 407, in which circuitrelay 407 also operates. The operation of relay 407 opens the circuit of magnet 467 and switch 460 comes to rest with its terminals engaging an idle district.

The'ope'ration of relay 407 also closes a circuit from battery through the winding of sequence switch magnet 400, upper con tact of cam 412, front contact of relay 407 to ground, in which circuit sequence switch 400 is advanced to position 8. In position 8 ground is connected 'over'the front contact of r l y 4% urr f' e i a e" an r s 466 and its associated contact, conductor 375 of the district selector just seized, lower right contact of cam 312, lower right contact of cam 313, left winding of relay 314 to battery. The operation of relay 31.4 closes a circuit from battery through the winding of sequence switch magnet 300, lower left contact of cam 328, outer right. front contact of relay 314, lower contact of cam 339, to ground advancing the sequence switch to position 2. The advance of sequence switch 300 to position 2 removes battery from conductor 366 permitting the release of relays 406 and 407. The release of relay 407 closes a circuit for advancing sequence switch 400 to position 9. The link circuit sequence switch remains in position 9 until the sequence switch of the next link circuit moves out of position 1 or 10 due to the receipt of a call as previously described. The dotted rectangle 450 represents the next link circuit. It will therefore be seen that when the sequence switch of link 450 moves fron position 1 to position 2 a circuit is closed from ground over cam 451, right contact of cam 452, lower contact of cam 422, upper contact of cam 423, winding of sequence switch magnet 400 to battery advancing sequence switch 400 to position 10. Sincethe link circuit performs two cycles of operation to one revolution of the sequence switch position 10 is the equivalent'of position 1 and the link circuit is now ready to respond to the reception of a call. The link circuit sequence switch now remains in position 10 and the sequence switch of the associated district in position 2 until another call is received.

At the termination ofthe conversation the selector switches are restored to normal as described in the above identified appli cation of O. H. Kopp. hen sequence switch 300 associated with the district selector reaches position 1 battery is disconnected from brush 381 and cut0ff relay 102 releases, restoring the subscribers line to normal in readiness for subsequent calls.

Vilhile the line finders and link circuits are divided into two groups each of which serve lines in par icular subgroups, the start circuit for Fig. 2 is so arranged that if all the link circuits in the group normally serving a particular calling line are busy, a link circuit and line finder of the other group will be employed.

hen all the link circuits belonging to one group are in use so that none of them has its sequence switch standing in position 1 or 10 a circuit is completed from ground at the contact of cam 453, of the last link circuit of the group, contact 017021111 454 of link circuit 450, contact of cam 424, conductor 425 winding of relay 203 to battery. Relay 208 operates and closes a circuit from battery through the left winding of relay 202, back contact of relay 203, left contact of relay 208 to ground. Relay 202 operates and disconnects conductor 131 from conductor 206 leading to the corresponding group of link circuits and transfers it over the back contacts of relays 209 and 210 to conductor 211 leading to the other group of link circuits. V hen now the allotted line finder in the second group starts, relay 210 is operated in a circuit from ground over conductor 212 (corresponding to conductor 207) left winding of relay 210, inner left back contact of relay 213 to battery. Relay 210 closes a locking circuit for relay 202 from battery through the right winding and right contact of relay 202, inner left front contact of relay 210 to ground, preventing the release of relay 202 should a link circuit in the first group become free before a calling line has been found. Similarly, if all the links circuits in the second group become busy, ground through all the link circuits of this group to conductor 214: will cause the operation of relay 215 which will operate relay 209. disconnect conductor 12? from conductor 211 and transfer it to conductor 206 leading to the first subgroup of link circuits.

. If for any reason a line finder fails to start within a reasonable time a circuit will be completed from ground at the outer right front contact of relay 110, outer le t front contact of relay 108, inner right front contact of relay 103, conductor 131, inner left back contact of relay 202, inner left back contact of. relay 203, contact of interrupter 216, left winding of relay 217 to battery. Relay 217 operates when interrupter 216 closes its lower contact and locks through its inner left front contact to the above traced circuit, independent of the interrupter contact. After an interval, when interrupter 216 closes its upper contact, the above traced circuit is extended over interrupter contact, outer left contact of relay 217, right winding of relay 205, left back contact of relay 213 to battery. Relay 205 operates and locks in a circuit from battery through the inner left front contact and left winding of relay 205, key 220 to ground. The operation of relay 205 closes a circuit from battery through the left winding of relay 202, outer right contact of relay 203, inner right contact of relay 205 to ground, transferring calls from the first to the second group of link circuits. Circuits are also closed for lamp 218 at the start circuit frame and lamp 219 at the trouble desk.

it will be clear from the foregoing dc scription that the arrangement of the present invention provides means for very rapidly associating a calling line with the district selector and register sender since a line finder is always held in readiness to serve a calling line and the sender selector of the link circuit operates during the time that the line finder is hunting. itccording to this arrangement, also, the use of link cirsuit and line finder-district selector units is distributed, thus producing even wear on he various pieces of apparatus.

lVhat is claimed is:

1. In a telephone exchange system, a plurality of subscribers lines divided into groups, a trip circuit for each group, a start circuit common to all groups, a plurality of link circuits, a plurality of line finders, a plurality of register senders, means in said link circuits for preselccting a line finder and means in said link circuit responsive to the initiation of a call over said trip, start and link circuits to said lino finder for hunting for an idle register sender.

In a telephone exchange system, a plurality of subscribers lines, a plurality of link circuits, a plurality of line finders, a plurality of register senders, nouns in said link circuits for preselecting a line finder, and means responsive to the initiation of a call from one of said subscribers liucs. through a link circuit to the preselected line finder for causing said preselected line finder to hunt for the calling line and for causing said link circuit to hunt for an idle sender.

3. In a telephone exchange system, a plurality of subscribers lines, a plurality of link circuits, means for extending a call from a subscribers line to one of said link circuits, a plurality of line finders, a plurality of register senders, means in said link circuit for preselccting a line finder, means for causing said preselected line finder to hunt for said calling line and means for simultaneously causing said link circuit to hunt for an idle sender.

l. In telephone exchange sysl'en'i, a plurality of subscribers lines. a plurality of link circuits, a plurality of line finders, means effective as soon as a link circuit becomes idlefor associating said link circuit with an idle line finuer, means for allotting said link circuits for use and means responsive to the initiation of a call from one of said subscribers lines over said alottcd link circuit, to allot the net-cl; link circuit.

In. a. telephone exchange system, a plurality of subscribers lines, a plurality o l lino finders, a plurality of link circuits, a. plurality of selector switchcs, means iuchuliug one of said link circuits for controlling the extension of a connection over one of said line finders and over said selector switches, means for releasing a link circuit as soon as a connection is completed, means for ca using said link circuit to immediately hunt for and connect with an idle line finder, means for maintaining all such idle link-line finder combinations in a sub-allotted condition, means for allott-ing one of said linkdine finder combinationsand means responsive to the extension of a call from one of said subscribers lines to said allotted link-line 'finder combination to allot the next idle combination.

6. In a telephone exchange system, a plurality of subscribers lines divided into groups, each group divided into subgroups, a. plurality of link circuits serving a particular subgroup in each of said groups of lines, a plurality of line finders, a plurality of selector switches, means including one of said link circuits for controlling the extension of connection over one of said line finders and over said selector switches, means for releasing a link circuit as soon as a connection is completed, means for causing said link circuit immediately thereupon to hunt for and connect with an idle line finder, means for maintaining all such idle link-line finder combinations in a suballotted condition, means for allotting one of said link-line finder combinations, means responsive to the extension of a call from one of said subscribers lines to said linkline finder combination to allot the next idle combination and means responsive to the employment of all the link-line finder combinations in one group to cause the allotted link-line finder combinations of said second group to serve calls in both groups of lines.

7. In a telephone exchange system, a plur'ality of subscribers lines divided into groups, each group divided into subgroups, a plurality of link circults serving a particular subgroup in each of said groups of lines, a

plu'ality of line finders, means el'lective as soon as a link circuit of each'subgroup be comes idle for assoc'iatingit ivith an idle line finder, means for allotting said link circuits for use, means responsive to the initiation'oi a call froma subscribers line in a subgroup to causethe allottmentof the next idle link circuit associated With such subgroup, and means responsive When all link circuits associated with a subgroup of lines are in use to cause the allotted link circuits associated with another subgroup to serve lines of both subgroups.

8. In a telephoneexchange system, a. plurality of subscribers lines divided into groups, each group divided into subgroups, a plurality of link circuits serving a particular subgroup in each of said groups of lines, a plurality of line finders, means effective as soon as a link circuit of each subgroup becomes idle for associating it, With an idle line finder, means for allotting said link circuits for use, means responsive to the initiation of a call in one subgroup over an allotted link circuit for causing the preselected line finder to hunt for the calling line, and means operative after a predetermined interval if said line finder fails to start hunting, to transfer said call to an allotted link circuit and preselected line finder of another subgroup.

In Witness whereof, I hereunto subscribe my name this 3rd day of October A. D., 1924.

WILLIAM H. MATTHIES. 

